1. Field of the Invention
The invention relates to devices and methods for treating urinary incontinence. More specifically, the invention relates to surgical devices and methods for eliminating or reducing urinary stress incontinence, particularly (though not exclusively) in minimally invasive surgical settings.
2. Description of Related Art
Urinary incontinence involves the involuntary passage of urine. A wide range of disorders and conditions can cause urinary incontinence, including injuries to the pelvic region, pregnancy/childbirth, infection, and degenerative changes associated with aging. In a healthy patient, on the other hand, urine remains in the bladder until the patient voluntarily causes it to flow through the urethra and out of the body.
Currently, an estimated 13 million Americans suffer some form of incontinence. As many as 85% of them are women, and indeed it is believed that as many as one in four women aged 30-59 has experienced at least one episode of urinary incontinence. Naturally, incontinence causes not only physical discomfort and inconvenience but also has emotional and psychological consequences as well.
Five forms of incontinence are generally recognized. Stress incontinence, an important focus of the present invention, often occurs when the pelvic muscles have deteriorated or been damaged. Coughing, sneezing, laughing, and other activities that put pressure on the abdomen and bladder may cause leakage. Stress incontinence is discussed further below. With another type of incontinence, known as urge incontinence, nerve passages between the bladder and brain are damaged. This damage causes sudden, seemingly uncontrollable bladder contractions that then cause leakage of urine. With overflow incontinence, the bladder's capacity is exceeded by the quantity of urine produced. Reflex incontinence, in which the patient generally is unaware of the need to urinate, can result from a leak in the bladder, urethra, or ureter, or an abnormal opening in the bladder. Finally, incontinence can be caused by certain surgical procedures involving e.g. the urethra or bladder neck. A single patient can have multiple forms of incontinence.
Stress incontinence often is caused by weakened muscles in the pelvic floor, as referenced earlier. Without adequate pelvic support, the bladder and proximal end of the urethra tend to sag, the bladder neck dilates, the proximal urethra widens, and the urethra as a whole shortens. Normal flow resistance from the bladder neck and the urethral sphincter decreases, causing leakage upon increase in intra-abdominal pressure that might be due to coughing, for example. FIG. 1 roughly illustrates three anatomical configurations with respect to pelvic floor 2: normal anatomy 4, descended bladder/urethra 6, and widened bladder neck/shortened urethra 8. FIG. 1 is adapted from Mundy, A. R., ed., Urodynamics--Principles, Practice and Application, 1984, p. 229. The Urodynamics text is incorporated by reference herein in its entirety.
Recent research suggests that incontinence requires multiple anatomic defects, not just one, and that the mere position of the urethra does not predict urinary incontinence. At least four anatomic factors are believed involved, namely, urethral length; support of the bladder neck and urethra by the pubo-urethral, urethropelvic, vesicopelvic and cardinal ligaments; changes in the bladder neck and urethra during times of stress; and coaptation of the urethra. The two most important factors in female urinary incontinence, recent research suggests, are hypermobility of the bladder neck and defective support of the midurethra. Note the discussion of this topic in "Anatomy of female continence redefined by photographs, imaging techniques," Urology Times of Canada, April, 1996, which is incorporated herein by reference.
Many varieties of general surgical procedures are used to treat stress incontinence. Most, if not all, such procedures involve open/endoscopic surgery and are significantly invasive, requiring general anesthesia and hospitalization. Such procedures are peri-urethral, i.e. they are performed from outside the urethra. Suspension procedures, for example, use sutures to lift the urethra and bladder neck to their normal positions. Sling procedures use synthetic material or tissue, often anchored to bone, to do the same. In some cases, an implantable artificial sphincter is used to restore the compressive action needed to stop the flow of urine.
Various invasive surgical procedures are described in the Urodynamics text referenced above. Additional discussion is found in Campbell's Urology, 5th ed., 1986, which is incorporated by reference herein. Additional methods and devices for treatment of incontinence are disclosed in, among others, U.S. Pat. Nos. 5,647,836, 5,611,515, 5,520,606, 5,417,226, 5,256,133, 5,234,409, 5,007,894, 4,857,041, 4,686,962, 4,139,006, 4,019,499, and 3,661,155, all of which are incorporated herein by reference.
As referenced above, most, if not all, known surgical procedures and devices for treating stress incontinence successfully are significantly invasive, complicated, or both. Significant trauma to the pelvic region can result. Additionally, although stress incontinence primarily affects females and thus the majority of known surgical procedures are directed at female patients, a significant number of males suffer stress incontinence as well. A need has arisen, therefore, to treat both female and male stress incontinence with minimal complexity and minimal invasiveness. Embodiments of the invention address complexity, invasiveness, and other problems.